what do abs,sin,cos etc mean?

Abs (short for absolute) basically makes any inputted number positive. Another way to see it is it returns how far the number is from 0.
https://www.mathsisfun.com/numbers/absolute-value.html

Sin, cos, and tan are also abbreviated (sine, cosine, tangent) and are used for trigonometry. https://www.mathsisfun.com/algebra/trigonometry.html

The Scratch Wiki has an article for this block and lots of explanations for each of the different options: https://en.scratch-wiki.info/wiki/()_of_()_(Operators_block)

Abs is absolute value which means that abs of -6 will be 6 and abs of 6 will remain 6. Sin Cos and Tan (Sine, Cosine and Tangent) are a part of trignometry which are the angles of a right triangle. These come very useful in scratch but you will learn it in 10th grade, i learnt it in 6th only just for fun, from Khan acedemy on youtube. They teach well, if you wanna learn trignometry then you can

what ways do you use sin cos and tan